Gun sight



United States Patent 3,184,851 GUN SIGHT Ernest P. Simmons, 2510Lafayette, Kansas City, Kans. Filed Jan. 10, 1963, Ser. No. 250,529 3Claims. (Cl. 33-47) This invention relates to new and usefulimprovements in gun sights, and has particular reference to a sight ofthe class commonly know as glowgsights such as used as the front sightsof shotguns. N

In glow sights, there is commonly provided a small cylindrical plug oftransparent or translucent material mounted at the forward end of ashotgun barrel, its axis being generally parallel to the barrel axis sothat the gunner sees only the rearward end thereof when sighting thegun. Light entering the plug along the exposed sides thereof is trappedtherein due to the fact that the plug is formed of .a material, such aslucite or certain other plastics, having an unusually high lightrefraction index. That is, an unusually high proportion of the lightentering the plug does not immediately emerge therefrom, but isreflected from the internal surfaces thereof, and tends to travellongitudinally along the plug, internally thereof, until it reaches theend of the plug and strikes the internal surface thereof at an anglestill greater than the refractive index thereof, whereupon it emergesfrom the plug. This elfect of confining or piping of light is wellknown, and is effective even to confine the light in a curved plug, soas to pipe the light around a corner, so long as the radius of curvatureis not too small. The effect is often used in medical instruments toilluminate areas of difiicult access. In gun sights as described, theeffect provides that the end of the plug will glow brightly and thusfacilitate the sighting operation. The brightness is further enhanced ifthe material of which the plug is formed is impregnated with luminescentdyes or the like.

An important object of the present invention is the provision, in a gunsight of the character described, of a special shape for the plug whichfurther enhances the brightness thereof, so that it will glow brightlyeven on very dull and cloudy days. Generally, this special shape isprovided by 'gl-o'dving the cylindrical side wall of the plug so as toprovide a large area thereof more nearly normal to the axis of the plug,so that more light will enter the plug at a small enough angle to saidaxis to be retained in the plug by internal reflection as describedabove.

Another object is the provision of a special mounting for the plugwhereby said plug, or more particularly the bead of bright lightailorded thereby, appears to rest directly on the gun barrel, ratherthan being spaced thereabove. In previous sights of this general type,to my knowledge, the necessity of a mounting piece for the plug causedthe plug to be elevated from the gun barrel, which rendered the line ofsight inaccurate as being angled upwardly from the axis of the barrel.In many guns, particularly guns wherein the front sight must beinstalled on the upper surface of a ventilated sighting rib extendingthe length of the barrel, the resultant inaccuracy necessitatedrealignment of the barrel. This realignment amounted to curving orbending the forward portion of the barrel upwardly so that the shotwould be discharged parallel to the line of sight.

Other objects are simplicity and economy of construction, efliciency anddependability of operation, and adaptability for use on many differenttypes and styles of guns.

With these objects in view, as well as other objects which will appearin the course of the specification, reference will be had to thedrawing, wherein:

FIG. 1 is a fragmentary side elevational view of the forward end portionof a shotgun barrel, with a sight embodying the present inventionmounted thereon,

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FIG. 2 is an enlarged fragmentary sectional view taken on line II--II ofFIG. 1,

FIG. 3 is a view similar to FIG. 1, showing the sight mounted on a gunincluding a ventilated sighting rib,

FIG. 4 is an enlarged fragmentary sectional view taken on line IVIV ofFIG. 3, and

FIG. 5 is a fragmentary sectional view taken on line VV of FIG. 2.

Like reference numerals apply to similar parts throughout the severalviews, and the numeral 2 applies to the barrel of a shotgun, only theforward end portion of said barrel being shown. The sight forming thesubject matter of the present invention is indicated generally by thenumeral 4, and is mounted at the top of the barrel immediately adjacentthe forward end thereof. Said sight includes a mount 6 and a plug 8.Mount 6 is formed of metal, and has the form of an elongated, upwardlyopening channel extending parallel to the axis of the barrel. Itincludes a planar base 10 having an upright vertical side wall 12 alongeach of the respective longitudinal edges thereof. Base 10 is providedcentrally with a downwardly extending threaded lug 14. When the sight isto be mounted directly on a gun barrel, as in FIGS. 1, 2 and 5, lug 14is screwed into a tapped hole 16 provided therefor in barrel 2, so thatthe lower surface of mount base 10 rests directly on the barrel asshown. In FIGS. 3 and 4, the shotgun is provided with a ventilatedsighting rib 18 which, as well understood in the art, comprises a metalbar extending the length of the barrel in spaced relation thereabove,the primary purpose of which is to interrupt the shimmering heat waveswhich arise from a hot gun barrel, whereby to provide a clear line ofsight. Said rib may be attached to the barrel by a series of posts, oneof which is shown at 20, said post being brazed or otherwise secured atits lower end to the barrel, and being provided at its upper end with adovetail head 22 engaged in a correspondingly shaped groove 24 formed inthe lower surface of the rib. In guns equipped in this manner, lug 14 ofthe sight mount is screwed into a tapped hole 26 formed therefor in therib, so that mount base 10 rests directly on the upper surface of therib. If the lug 14 projects slightly into barrel 2, as shown in FIGS. 2and 5, or into rib groove 26, the projecting portion may be ground offif desired.

Plug 8 is formed of a plastic or other transparent or translucentmaterial having a high light refraction index, and is generallycylindrical in form, having hemispherically curved end portions 28. Thelength of the cylindrical portion thereof corresponds to thelongitudinal length of mount base 10, and a notch 30 is formed in thelower surface of said plug for engaging the mount base. Longitudinallyof the lug, the length of notch 30 is equal to the length of thecylindrical portion thereof, and hence equal to the length of the mountbase. Vertically, the depth of the notch is equal to the verticalthickness of the mount base. Hence when the plug is placed in the mountso that notch 30 engages the mount base, the hemispherically curved endportions 28 of the plug will appear to rest directly on the gun barrel,as in FIGS. 1, 2 and 5, or directly on rib 18, as in FIGS. 3 and 4. Thediameter of the plug is equal to the spacing between side walls 12 ofthe mount. Said side walls extend above the axis of the plug, and theupper edge portions 32 thereof are rolled inwardly as best shown inFIGS. 2 and 4 to secure the plug in assembly with the mount. The upperportion of the plug which is exposed between the upper edges of sidewalls 12 has a continuous series of peripheral grooves 34 formedtherein.

In operation, light striking the exposed surfaces of the plug from agenerally forward angle will be partially refiected therefrom and willpartially enter therein, and that part of the light which enters tendsto be trapped therein,

as previously described, by internal reflection resulting from the highrefractive index of the plug material, until it reaches the rearward endof the plug where it emerges therefrom since it strikes the internalsurfaces at said end at angles too obtuse for internal reflection,thereby giving the appearance ofabrightly. glowing head of @which is ofmaterial assistance in the operation of sighting the gun. The grooves 34have been found to be of material assistance in providing a brighterlight, even on very dull and cloudy days, apparently because theyprovide a much greater surface area, namely the forwardly facing wallsof the grooves, which is disposed more nearly normal to the axis of theplug, so that a greater portion of the light in this direction entersthe plug rather than being reflected externally therefrom. The shape ofthe grooves should be such that the forwardly facing walls formedthereby direct light entering therethrough angularly toward the oppositeside of the plug for internal reflection at the opposite side ratherthan directing it parallel to the plug axis toward the next groove,where it would merge and be lost. For this reason, square groovesforming walls at right angles to the plug axis have been foundrelatively ineffective. At the same time, the forwardly facing walls ofthe grooves should not be so acutely angled to the plug axis that lightentering them is directed to the opposite side at such an angle as toemerge therefrom rather than being internally reflected. Tests indicatethat these groove walls should be inclined to the plug axis at an angleof at least 45 degrees. V-shaped grooves with a total included angle of60 degrees, as shown, have been the most effective yet tested, but thisis not intended as restrictive. Providing the inner surfaces 36 of baseand side walls 12 with a high polish also increases the brightness ofthe sight, as they will then reflect and return to the plug at least aportion of the light which would otherwise be lost.

Notching the plug at 30 to receive mount base 10 therein, so that thehead of light afforded by the sight appears to rest directly on the gunbarrel, or on the surface of sight rib 18, greatly reduces, and in thecase of a sight mounted directly on the barrel entirely eliminates, thenecessity of bending or realigning the barrel to compensate forelevation of the sight which usually results from the mounting of asight of this type. Nor is the lower part of the light head as viewed bythe gunner darkened by the presence of mount base 10 therebehind. Theplug extends well behind the mount, and the extending portion ishemispherically curved. This curvature diffuses the available lightthoroughly throughout the entire height of the plug. It has been foundthat so long as the rearwardly extending portion 28 of the plug is of atleast full hemispherical extent, and so long as the vertical thicknessof mount base 10 is no more than about onethird the radius of the plug,there will be no apparent darkening of the lower portion of the lightbead as viewed by the gunner.

While I have shown and described a specific embodiment of my invention,it will be readily apparent that many minor changes of structure andoperation could be made Without departing from the spirit of theinvention as de fined by the scope of the appended claims.

What I claim as new and desire to protect by Letters Patent is:

l. A gun sight comprising:

(a) a generally cylindrical plug of translucent material having a lightrefractive index, and means for mounting said plug rigidly relative to agun barrel with its axis generally parallel to the axis of said barreland with at least a portion of its cylindrical surface exposed, saidexposed surface having a series of grooves formed peripherally therein,said mounting means including a channel-shaped mount of substantiallyU-shaped cross-sectional contour having a planar base and a pair ofparallel side walls disposed respectively at opposite sides of saidbase, said base being adapted to engage the barrel of said gun directly,said plug being disposed longitudinally in said mount and having one endthereof projecting outwardly from said mount, said plug having a notchformed in the lower portion thereof receiving the base of said mount,the vertical depth of said notch corresponding to the vertical thicknessof said base so that the projecting end portion of the plug, when viewedaxially of said plug, appears to rest directly on said gun barrel.

2. A gun sight as recited in claim 1 wherein the projecting end portionof said plug is hemispherically rounded.

3. A gun sight as recited in claim 1 wherein the projecting end portionof said plug is hemispherically rounded, and wherein the verticalthickness of said mount base is no greater than about one-third of theradius of said plug.

References Cited by the Examiner UNITED STATES PATENTS 2,181,081 11/39Ganaway 33-52 X 2,610,405 9/52 Dickinson 33-47 2,706,335 4/55 Munsey33-47 2,727,309 12/55 Jenkins 33--52 2,911,724 11/59 Conant 33523,040,168 6/62 Stearns 2401 X ISAAC LISANN, Primary Examiner.

1. A GUN SIGHT COMPRISING: (A) A GENERALLY CYLINDRICAL PLUG OFTRANSLUCENT MATERIAL HAVING A LIGHT REFRACTIVE INDEX, AND MEANS FORMOUNTING SAID PLUG RIGIDLY RELATIVE TO A GUN BARREL WITH ITS AXISGENERALLY PARALLEL TO THE AXIS OF SAID BARREL AND WITH AT LEAST APORTION OF ITS CYLINDRICAL SURFACE EXPOSED, SAID EXPOSED SURFACE HAVINGA SERIES OF GROOVES FORMED PERIPHERALLY THEREIN, SAID MOUNTING MEANSINCLUDING A CHANNEL-SHAPED MOUNT OF SUBSTANTIALLY U-SHAPEDCROSS-SECTIONAL CONTOUR HAVING A PLANAR BASE AND A PAIR OF PARALLEL SIDEWALLS DISPOSED RESPECTIVELY AT OPPOSITE SIDES OF SAID BASE, SAID BASEBEING ADAPTED TO ENGAGE THE BARREL OF SAID GUN DIRECTLY, SAID PLUG BEINGDISPOSED LONGITUDINALLY IN SAID MOUNT AND HAVING ONE END THEREOFPROJECTING OUTWARDLY FROM SAID MOUNT, SAID PLUG HAVING A NOTCH FORMED INTHE LOWER PORTION THEREOF RECEIVING THE BASE OF SAID MOUNT, THE VERTICALDEPTH OF SAID NOTCH CORRESPONDING TO THE VERTICAL THICKNESS OF SAID BASESO THAT THE PROJECTING END PORTION OF THE PLUG, WHEN VIEWED AXIALLY OFSAID PLUG, APPEARS TO REST DIRECTLY ON SAID GUN BARREL.